Analysis Trustwave's admission that it issued a digital "skeleton key" that allowed an unnamed private biz to spy on SSL-encrypted connections within its corporate network has sparked a fiery debate about trust on the internet.

Trustwave, an SSL certificate authority, confessed to supplying a subordinate root certificate as part of an information security product that allowed a customer to monitor employees' web communications - even if the staffers relied on HTTPS. Trustwave said the man-in-the-middle (MitM) gear was designed both to be tamper-proof and to work only within its unnamed client's compound. Despite these precautions, Trustwave now admits that the whole approach was misconceived and would not be repeated. In addition, it revoked the offending certificate.

Trustwave came clean without the need for pressure beforehand. Even so its action have split security experts and prompted calls on Mozilla's Bugzilla security list to remove the Trustwave root certificate from Firefox.

Death sentence debate

Critics claimed that Trustwave had enabled its client to issue arbitrary SSL certificates for any domain - this is in violation of Mozilla's policy against "knowingly issuing certificates without the knowledge of the entities whose information is referenced in the certificates". Trustwave sold a certificate knowing that it would be used in man-in-the-middle eavesdropping of encrypted information, an insecure practice that it ought to have never used in the first place.

Researcher and privacy advocate Christopher Soghoian weighed into the debate on Mozilla's list with the case for the prosecution.

"Trustwave sold a certificate knowing that it would be used to perform active man-in-the-middle interception of HTTPS traffic," he wrote. "This is very very different than the usual argument that is used to justify 'legitimate' intermediate certificates: the corporate customer wants to generate lots of certs for internal servers that it owns.

"Regardless of the fact that Trustwave has since realized that this is not a good business practice to be engaged in, the damage is done."

Soghoian concluded: "With root certificate power comes great responsibility. Trustwave has abused this power and trust, and so the appropriate punishment here is death (of its root certificate)."

Those defending Trustwave suggested that other vendors probably used the same approach for so-called "data loss prevention" environments - systems that inspect information flowing through a network to prevent leaks of commercially sensitive data. It would be wrong to impose a death sentence on Trustwave as a certificate authority after it came clean and abandoned the MitM digital certificate technique, the counterargument goes.

"Personally, I think Trustwave should be commended for being the first CA [certificate authority] to come forward, admit to, and renounce this practice of issuing unrestricted 3rd-party sub-CAs," Marsh Ray, a researcher and software developer at two-factor authentication service PhoneFactor, wrote in the Mozilla debate.

"When I read Mozilla's policy, and the CA/B Forum baseline requirements, I see enough wiggle room in there that someone might plausibly claim that some agreed-upon scenarios for MitM certs was not prohibited by the agreement. In fact Geotrust was openly advertising a 'Georoot' product on their website until fairly recently.

"Those who are advocating Trustwave's removal from the list would seem to be of the belief that Trustwave was somehow alone in this practice. As I do not hold that belief, I think it would be a mistake to continue to threaten Trustwave and discourage other CAs from coming forward at this time."